1. Field of the Invention
The present invention relates to a three-dimensional (3D) display system, and more particularly, to a 3D display system that synthesizes a 3D image and position information data of an observer obtained through a camera with an optimal viewing area image with respect to horizontal and vertical directions of a display panel in a 3D space, and displays the synthesized image on the display panel to let the observer visually know an optimal viewing area, thereby enabling the at least one observer to visually check the optimal viewing area with ease and inducing the observer to move to a position in the optimal viewing area.
2. Discussion of Related Art
In general, a stereo image representing three dimensions is obtained according to the principle of stereo vision. Here, parallax between two eyes, that is, binocular disparity caused by a distance of about 65 mm between two eyes, is the most crucial factor to experiencing stereoscopy.
Specifically, the left and right eyes see different 2D images, which are delivered to the brain through the retinas. Then, the brain fuses the 2D images together, thereby reproducing depth and actuality of the original 3D image.
Technology that has been hitherto disclosed to display 3D images includes stereo image display methods with special glasses, stereo image display methods without glasses, and holographic display methods.
Among these methods, the stereo image display methods with special glasses may be classified into a polarized-glass method that utilizes a vibration direction or rotation direction of polarized light, a shutter glass method in which left and right images are alternately displayed, and a Pulfrich method in which types of light having different brightness are delivered to each of the left and right eyes.
Also, the stereo image display methods without glasses may be classified into a parallax method that enables separate observation of respective images corresponding to the left and right eyes through apertures having a vertical lattice shape in front of the images, a lenticular method that utilizes a lenticular plate on which semicylindrical lenses are arranged, and an integral photography method that utilizes a fly's eye lens sheet.
The holographic display methods may yield 3D images having all factors of a stereoscopic feeling such as accommodation, convergence, binocular disparity, and motion parallax, which are classified into laser reproduction holograms and white-light reproduction holograms.
The stereo image display methods with special glasses enable many people to enjoy stereo images but require them to wear polarized glasses or liquid crystal shutter glasses. In other words, observers need to wear special glasses and thus feel uncomfortable and unnatural.
Meanwhile, the stereo image display methods without glasses have a fixed observing range for a small number of people, but are preferred because they enable observation without special glasses. In other words, observers directly view a screen, and thus the above-mentioned drawback is eliminated. For this reason, active research is under way on the stereo image display methods without glasses.
Perfect 3D images can be displayed using, for example, the holographic display methods, which directly display images based on 3D coordinates in a space using a laser, lens, mirror, and so on. The holographic display methods give the feeling of an actually existing object. However, due to technological difficulties and a large space occupied by equipment, the holographic display methods are difficult to use.
Consequently, there is a growing tendency to employ stereoscopic display methods that provide the amount of parallax of each object through a stereo image and thereby cause an observer to feel the depth of the object. In stereoscopic displaying, viewing zone-forming optical system for stereo vision is used. Typical viewing zone-forming optical system utilizes a parallax barrier method that forms a viewing zone of each view image using a barrier, and a lenticular lens sheet method that forms a viewing zone of each view image using the light-collecting effect of a cylindrical lens. The two methods are primarily aimed at the function of forming a viewing zone of the corresponding view image. In the two methods, respective view images have the same center, and the two methods can be selectively used according to characteristics of systems.
In the parallax barrier method, vertical or horizontal apertures or slits are put in front of an image corresponding to both the left and right eyes, and the synthesized stereo image is separately viewed through the apertures or slits, thereby giving a stereoscopic feeling.
A 3D image display apparatus employing the parallax barrier method will be briefly described below.
FIG. 1 illustrates implementation of a 3D image performed by an existing parallax-barrier 3D display apparatus.
Referring to FIG. 1, in the existing parallax barrier method, a parallax barrier panel 20 formed by repeatedly arranging an aperture through which light emitted from a display panel 30 is transmitted and a barrier that blocks the light is repeatedly disposed in front of the display panel 30.
An observer 10 sees an image displayed or printed on the display panel 30 through the apertures of the parallax barrier panel 20. At this time, a left eye L and a right eye R of the observer 10 see different regions of the display panel 30 even through the same aperture. In the parallax barrier method using such a principle, left and right eyes see images corresponding to pixels of different regions, such that stereoscopy can be experienced. Specifically, in FIG. 1, the left eye L sees a left eye-corresponding pixel Lp in the display panel 30, and the right eye R sees a right eye-corresponding pixel Rp in the display panel 30.
Also, the lenticular lens method biases view image information by the refractive power of lenslets using a lenticular lens sheet instead of a parallax barrier, and thereby can form the same viewing zone for each view image as in an environment in which a parallax barrier is used. In other words, on the basis of the same mechanism, both the methods divide view information to provide a stereoscopic effect.
However, by causing both eyes to separately see an image, a 3D display apparatus based on the existing parallax barrier method or lenticular lens method gives a stereoscopic feeling to a predetermined position only. Outside the predetermined position, left and right images are inverted or the image is inappropriately separated in the left and right directions, and thus a distorted 3D image is observed.